Siege of Stralsund (1628)

The Siege of Stralsund occurred from May to 4 August 1628 during the Thirty Years' War. The German Catholic army of Albrecht von Wallenburg failed to capture the Baltic Sea port of Stralsund due to the intervention of Denmark (whose army included a large number of Scottish troops) and Sweden, marking the start of Sweden's intervention in the war.

Background
During the Low Saxon War, the Catholic mercenary general Albrecht von Wallenstein succeeded in defeating the Danish army of King Christian IV of Denmark in northern Germany and conquering Holstein, forcing Christian to withdraw into Denmark. He was then made Duke of Mecklenburg in a move which even shocked fellow Catholics. He wanted another base for his burgeoning fleet, and he was convinced to focus on the Hanseatic League town of Stralsund, which was known for resisting ducal authority.

Siege
In May 1628, Wallenstein sent his general Hans Georg von Arnim-Boitzenburg to besiege Stralsund, but he only implemented a loose blockade, fearing that Imperial reputation would be harmed if he launched an all-out assault. The poorer citizens of Stralsund resolved to fight back against the mercenary army, and its citizen force of 2,500, a levy of 1,500 troops, and a few hundred mercenaries decided to defend the city from Wallenstein's forces. Wallenstein seized the island of Danholm on the eastern edge of the harbor, placing the city within range of his cannons, but Arnim had no fleet to resupply his force, and the small Stralsund navy blockaded Danholm until the Imperial forces surrendered on 15 April. Over the next month, 6,000 Imperial reinforcements arrived, and Arnim launched a failed night assault. Christian IV of Denmark then sent 1,000 Scots and Germans under Heinrich Holk to assist the town, and, after a few more small-scaled repulsed attacks from 26 to 27 May, Arnim launched massed artillery bombardments. 600 more reinforcements arrived under the Swedish flag, and the town began a 20-year alliance with the Swedish king Gustavus Adolphus, who garrisoned the town. On 27 June, Wallenstein arrived in person and assumed command of the army, renewing the assaults with great intensity. The Scots under Robert Munro defended the eastern district of Franken and repulsed the attackers, although 500 of the 900 Scots were killed and a further 300 were wounded, including Munro himself. The following night, the outer fortifications fell, but Wallenstein could not press any further, and instead resumed his bombardments. Stralsund still refused to surrender, and, on 30 June, more Swedish vessels arrived with 600 reinforcements. On 17 July, Alexander Leslie arrived with 1,000 more Scots and launched a successful sortie against the Imperial siege lines. A week later, the battlefield was turned into a sea of mud by rainfall, and, on 4 August, Wallenstein lifted the siege, his first defeat.